I am not sure what other weapons are bugged like this but the rapier Rannig's Wrath is  - the weapon loses its existing enchants (melee accuracy, action speed) if you start adding the other special enchants like flanking bonus or penetration on crit.

 

Original:

 

 

After upgrade:

 

 

I checked on my stats and the modifier is literally gone because my character screen doesn't report getting the buff from the flurry any more.

 

This is not the case with other weapons that I've tried - they retain their special properties and have the enchanted ones added on top instead of being replaced by them. 

Edited May 22, 20187 yr by Infiltrator_SF

Yeah, I have noticed that too. It would be nice to know if it is a bug, or intended.

Was this fixed?

Greetings,

 

And thank you for bringing this issue to our attention We'll add this to our date-base for our Developers to investigate further.

 

Cheers.